In Mexico, the violence generated by drug trafficking organizations (DTOs) in recent years has been, according to some, unprecedented. In 2006, Mexico's newly elected President Felipe Calderón launched an aggressive campaign--an initiative that has defined his administration-- against the DTOs that has been met with a violent response from the DTOs. Government enforcement efforts have had successes in removing some of the key leaders in all of the seven major DTOs. However, these efforts have led to violent succession struggles within the DTOs themselves.